Related Experiment Video

Updated: Jul 10, 2026

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus
09:08

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus

Published on: July 27, 2021

Double-ring assembly of mpox virus I3L reveals an unconventional mechanism for ssDNA engagement

Kankan Yang1, Mengrui Ge1, Jinmiao Song1

  • 1Institute of Infectious Diseases, Shenzhen Bay Laboratory, Shenzhen 518132, China.

Cell Reports
|July 8, 2026
PubMed

Insights

The mpox virus (MPXV) single-stranded DNA-binding protein (SSB) I3L forms a unique double-ring structure essential for viral DNA replication. This discovery reveals a specialized mechanism for poxvirus genome maintenance and potential antiviral targets.

Area of Science:

  • Virology
  • Structural Biology
  • Molecular Biology

Background:

  • Poxviruses, such as mpox virus (MPXV), are large DNA viruses replicating in the host cytoplasm.
  • The single-stranded DNA-binding protein (SSB) I3L is crucial for poxviral genome replication, but its structure and mechanism are not fully understood.

Purpose of the Study:

  • To elucidate the structural mechanism of MPXV I3L and its interaction with single-stranded DNA (ssDNA).
  • To understand the specialized molecular mechanisms underlying poxviral DNA replication.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) to determine the structure of MPXV I3L.
  • Structural modeling of the MPXV I3L-ssDNA complex.
  • Biochemical assays to investigate ssDNA binding.

Main Results:

  • The cryo-EM structure revealed that MPXV I3L forms a unique double-ring assembly, distinct from canonical SSBs.
  • The I3L protomer exhibits an OB-fold variant with specialized structural elements.
  • ssDNA engagement is dependent on the assembly, while monomeric binding retains conserved features.

Conclusions:

  • MPXV I3L possesses distinctive structural features enabling a specialized mechanism for poxviral DNA replication.
  • This research advances the understanding of poxvirus genome maintenance.
  • The findings offer insights for developing novel antiviral strategies against MPXV.
Keywords:
CP: genomicsCP: immunologyDouble-ring assemblyI3L proteinMpox virusOB-foldPoxvirusesSingle-stranded DNA-binding protein (SSB)Viral DNA replication machinery

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